A challenge for single shaft steam turbine plants with steam off-takes for high demand users is to operate in an efficient manner while minimizing shaft peak torque stress. Peak torque can be created by the difference between the resistance created by a generator, for example, located on the shaft, and a series of steam turbines.
A carbon capture and sequestration unit in an example of a high demand steam consumer, is described in EP 1688173. Known steam turbine plant arrangements for the efficient supply of energy and steam to the high demand steam consumer are described in Zachary, J (June 2008), “Options for reducing a coal-fired plant's carbon foot print: Part I”, POWER 28-33 (Zachary). The described arrangements include single shaft steam turbines arranged in series with multiple low pressure steam turbines. U.S. Patent Application No. US 2010/0038917 discloses a single shaft steam turbine plant with intermediate off-takes for a high demand user.